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  1. Fifth Wheel King Pin
  2. CURT
  3. Lippert 1621
  4. 21000 lbs GTW
  5. Upgraded Pin Box
  6. Absorbs Road Shock and Reduces Chucking
Curt Rota-Flex 5th Wheel Pin Box - Lippert 1621 - 21,000 lbs

Curt Rota-Flex 5th Wheel Pin Box - Lippert 1621 - 21,000 lbs

Item # LC328329
Retail:$1,120.89
Our Price: $678.90
You Save: $441.99
Fifth Wheel King Pin
Shipping Weight: 115 lbs
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This Rota-Flex pin box has a pivoting head with a built-in rubber compound that works to reduce chucking and absorb road shock, resulting in a smoother ride and less wear and tear on your trailer. Replaces Lippert 1621 pin boxes. 1-800-940-8924 to order CURT fifth wheel king pin part number LC328329 or order online at etrailer.com. Free expert support on all CURT products. Great prices and Fastest Shipping for Curt Rota-Flex 5th Wheel Pin Box - Lippert 1621 - 21,000 lbs. Fifth Wheel King Pin reviews from real customers.
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  • Reviews (30)
  • Q & A (0)
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CURT Fifth Wheel King Pin - LC328329

  • Lippert 1621
  • 21000 lbs GTW
  • Upgraded Pin Box
  • CURT
  • Absorbs Road Shock and Reduces Chucking
  • Fixed Turret

This Rota-Flex pin box has a pivoting head with a built-in rubber compound that works to reduce chucking and absorb road shock, resulting in a smoother ride and less wear and tear on your trailer. Replaces Lippert 1621 pin boxes.


Features:

  • Pivoting pin box replaces standard pin box on your 5th-wheel trailer to improve handling and limit strain on the truck and trailer
    • Minimizes chucking by allowing controlled movement of king pin within your hitch
  • Rubber compound built into the head absorbs road shock
    • Reduces wear and tear on trailer
  • Black powder coat provides rust resistance
  • Sturdy steel construction
  • King pin connects to any 5th-wheel trailer hitch
  • Bolt-on installation with no assembly required
  • Made in the USA


Specs:

  • Designed to replace Lippert 1621 5th-wheel pin box
  • Weight capacity: 21,000 lbs
  • 1-Year limited warranty


Diagram of measurements for the Curt Rota-Flex pin box

Notes:

  • Do not use the Curt Rota-Flex pin box with any type of gooseneck adapter.
  • The Curt Rota-Flex is not compatible with Curt E-Series or Q-Series 5th wheel hitches.

The Rota-Flex pin box has a pivoting head and built-in rubber compound that help to reduce checking and absorb road shock for a smoother ride as you tow your fifth-wheel trailer.


Pivoting Head Reduces Chucking

The Curt Rota-Flex pin box has a pivoting head to help reduce chucking

The pivoting head on the Rota-Flex allows for controlled back and forth movement of the king pin to reduce the uncomfortable jarring known as chucking. Unlike a rigid pin box that has little give at the point where the trailer and the hitch are connected, the Rota-Flex can pivot slightly to compensate for those times that your trailer suddenly pushes or pulls on your tow vehicle. Because the pin box head - not the king pin itself - is moving, the chucking that often occurs when the king pin jerks around inside the hitch is significantly reduced.


Rubber Compound Absorbs Road Shock

The Curt Rota-Flex pin box has a built-in rubber compound to help absorb road shock

A heavy-duty rubber compound is built into the head assembly of the Rota-Flex pin box. This rubber absorbs the bumps and vibrations, or road shock, experienced when towing a fifth-wheel trailer over rough roads. Standard pin boxes without any type of shock absorption transfer road shock to your trailer, resulting in potential damage to the trailer and an overall bumpy ride. The shock-absorbing rubber inside the Rota-Flex takes the beating so there's less wear and tear on your trailer or RV and you get a smoother ride.


Easy, Bolt-On Installation

The Rota-Flex is easy to install. Simply remove your existing Lippert 1621 pin box and install the Rota-Flex on your trailer or RV. The Rota-Flex uses the same bolts that held on your original pin box so no additional hardware is required. Plus, it comes out of the box ready to be put on your trailer, so no assembly is needed. Because the Rota-Flex is quite heavy, you should put it on an elevated surface or have a friend help you support its weight during installation.



328329 Curt Rotaflex Fifth Wheel Kingpin Box for Lippert 1621

Replaces 328329 Lippert Components (LCI) Rotaflex by Trail Air Fifth Wheel Kingpin Box for Lippert 1621

Installation Details LC328329 Installation instructions



Customer Satisfaction Score:


Customer Reviews

Curt Rota-Flex 5th Wheel Pin Box - Lippert 1621 - 21,000 lbs - LC328329

Average Customer Rating:  4.6 out of 5 stars   (30 Customer Reviews)

This Rota-Flex pin box has a pivoting head with a built-in rubber compound that works to reduce chucking and absorb road shock, resulting in a smoother ride and less wear and tear on your trailer. Replaces Lippert 1621 pin boxes.

by:

The cardboard box the hitch was delivered in was damaged, hitch was not damaged. Curt could potentially package the hitch differently to protect the product and mitigate delivery damage.



by:

> haven taken trip yet but i know there be a huge difference in the ride



by:

Haven't installed pin box yet but it was delivered uncrated, and it looked like it was a used pin box.



by:

I received the pin box in good condition. Preparing to install. Much anticipation to get rid of present air ride hitch which is woefully inadequate.



by:

Great service and fast shipping!! Great King pin . But wouldn’t fix my 5 wheel pin box.



by:

Switched from a ball. Glad I did. Very well pleased.



by:

Great quality, great customer service - I’ll use E-trailer for everything I can now!



by:

Great product, unfortunately I was very displeased with how it was delivered. The product was unwrapped and had the potential to be scratched up and chipped.

Etrailer Expert

Sierra K.

12/27/2021

Customer service will reach out to you. It is important to cover all bare metal with anti-corrosive paint to avoid rust. I have attached a help article regarding this.



by:

Helps take the bumps out of our wonderful roads.



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Nice pin box



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Drove well



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I have had many coach's with this hitch, that is why I am changing out the one currently in the coach to this.

UPS delivery sucks. Box was misrouted to another terminal after arriving at the facility near me. Caused an extra day's delay in delivery. When box did finally arrive it was virtually destroyed and driver claimed box showed up open and that they had to retape it this morning ING before delivering it.



by:

I've had this pin box on other fifth wheel trailers with great experience.



by:

It's a great pinbox. Really helped with chucking and compatible with my Demco sliding hitch. Also no issues with delivery, was helped by Pam and Jessie. They are awesome people to work with.



by:

Perfect replacement for my unit. The movement in the mount helps with the shock on the hitch itself. The unit is very strong and after a year I have had no problems. The instructions were spot on and shipping was very fast. I recommend this pin box as it is more economical than others I have seen but really helps on the bump and pull with a solid hitch



by:

The shipping container was not adequate for pin box. It was too large and no protective packing was used to protect the powder coated finish. When it was delivered by UPS the carton was destroyed. I had to repaint it as it was badly chipped from rough handling. I am disappointed in the performance as I do not see any difference in the chucking which is the reason why I purchased it. If I were to get a different 5th wheel I will not purchase a Rota-Flex again.



by:

Received on Wed. as planned. With a little help from my forklift, I had this trail air pin box installed in few hours. Fit perfect on my Sabre. Drove around the block, about 4 miles. This pulls so nice, it is like nothing behind you. Thanks etrailer.



by:

Looks great on my 5th. If anyone else has wondered as I did and could not find anything online regarding the vertical height difference between this trail air rota flex and my standard lippert 1621. This pin box will reduce the nose of my 5th by 2" mounted in the same location. Now to pull my rear axle spacers on my dodge to get another 1.5" lower. Etrailer is great as always. Never had a problem with them and have ordered here many times. Thanks Etrailer!



by:

Got it on and ready to try. It fit nicely. Did it myself in about an hour . Nothing left of the box it was in but other than a couple of scratches the pin box itself was in good condition



by:

The product was great, The better part was how fast it got to me . I had it put on the camper the same day i had received it what was 3 days after my order. Now you can't beat the shipping. All my orders from ETrailer has been fast and on time . Thank you all at Etrailer.


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Show More Reviews

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Info for this part was:

Employee Lindsey S
Edited by:
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Employee Michael H
Expert Research:
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Employee Jeffrey L
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